如何使用复选框小部件将条目窗口小部件的状态从禁用更改为未禁用？

Question

我使用tkinter 8.6与python 3.5.2，我试图创建一个图形用户界面，所以当我点击一个复选框，它允许用户写入输入框中的东西。但是我收到一个错误。以下是我的代码。

from tkinter import * 
from tkinter import ttk 

def quit(): 
    mainframe.quit() 

#Write in Function 
def write(): 
    write_in.state(['!disabled']) #Getting Error Here 

root = Tk() 
root.title("Voting Booth") 

#Global variables 
var = StringVar() 

#Create main widget 
mainframe = ttk.Frame(root, padding="3 3 12 12") 
mainframe.grid(column=0, row=0, sticky=(N, W, E, S)) 
mainframe.columnconfigure(0, weight=1) 
mainframe.rowconfigure(0, weight=1) 

#Additional widgets 
ttk.Label(mainframe, textvariable=var, font=('bold')).grid(column=2, row=0) 
vote = ttk.Button(mainframe, text="Vote", command = quit).grid(column=4, row=5, sticky=E) 
don_box = ttk.Checkbutton(mainframe, text="Donald Trump").grid(column=2, row=1, sticky=W) 
stein_box = ttk.Checkbutton(mainframe, text="Jill Stein").grid(column=2, row=3, sticky=W) 
write_box = ttk.Checkbutton(mainframe, text="Write in:", command = write).grid(column=2, row=4, sticky=W) 
write_in = ttk.Entry(mainframe, width = 20, state=DISABLED).grid(column=3, row=4, sticky=W) 

#Setting variables and widgets 
var.set("Presidential Nominees") 

for child in mainframe.winfo_children(): child.grid_configure(padx=5, pady=5) 

root.mainloop(); 

但是我收到以下错误，当我点击write_in复选框：

" File "/usr/lib/python3.5/tkinter/__init__.py", line 1553, in __call__ 
return self.func(*args) 
File "./booth_gui.py", line 13, in write 
write_in.state(['!disabled']) 
AttributeError: 'NoneType' object has no attribute 'state' " 

Answer 1

你得到一个NoneType异常，因为write_in对象实际上是None。

的问题是，你声明write_in为：

write_in = ttk.Entry(...).grid(column=3, row=4, sticky=W) 

但grid方法返回一个None结果。

到grid的调用必须从窗口小部件声明分开：

write_in = ttk.Entry(...) 
write_in.grid(column=3, row=4, sticky=W) 

---

关于你改变控件的状态的样子，我真的不知道它应该工作。

尝试使用config（或configure）插件方法和state关键字设置为NORMAL：`self.vote = ttk.Button（自：

write_in.config(state=NORMAL) 

Answer 2

这里是一个完整的解决方案：

import tkinter 
from tkinter import ttk 

class MyApp: 
    def __init__(self): 
     self.root = tkinter.Tk() 
     self.root.title('Voting Booth') 

     self.labelvar = tkinter.StringVar() 
     self.votevar = tkinter.StringVar() 
     self.writevar = tkinter.StringVar() 

     self.mainframe = ttk.Frame(self.root, padding="3 3 12 12") 
     self.mainframe.grid(column=0, row=0, sticky='nsew') 
     self.mainframe.columnconfigure(0, weight=1) 
     self.mainframe.rowconfigure(0, weight=1) 

     self.label = ttk.Label(self.mainframe, textvariable=self.labelvar, font=('bold')) 
     self.vote = ttk.Button(self.mainframe, text='Vote', command=self.quit) 
     self.don_box = ttk.Radiobutton(self.mainframe, text='Donald Trump', variable=self.votevar, value='trump', command=self.write) 
     self.stein_box = ttk.Radiobutton(self.mainframe, text='Jill Stein', variable=self.votevar, value='stein', command=self.write) 
     self.write_box = ttk.Radiobutton(self.mainframe, text='Write in: ', variable=self.votevar, value='write', command=self.write) 
     self.write_in = ttk.Entry(self.mainframe, textvariable= self.writevar, width=20, state='disabled') 

     self.label.grid(column=2, row=0) 
     self.vote.grid(column=4, row=5, sticky='e') 
     self.don_box.grid(column=2, row=1, sticky='w') 
     self.stein_box.grid(column=2, row=3, sticky='w') 
     self.write_box.grid(column=2, row=4, sticky='w') 
     self.write_in.grid(column=3, row=4, stick='w') 

     self.labelvar.set('Presidential Nominees') 

     for child in self.mainframe.winfo_children(): 
      child.grid_configure(padx=5, pady=5) 

    def quit(self): 
     self.root.destroy() 

    def write(self): 
     if self.votevar.get() == 'write': 
      self.write_in['state'] = 'normal' 
     else: 
      self.write_in['state'] = 'disabled' 
      self.writevar.set('') 

    def run(self): 
     self.root.mainloop() 

MyApp().run()